Patent GB-855135-A (GB)
Title: Improvements relating to steam cycles
IPC: F01K3/00
Filed: 1957-04-12
Abstract: 855,135. Mixing gases in flow. SONNEFELD, G. April 12, 1957 [April 13, 1956], No. 12052/57. Class 86 [Also in Group XXVI] A nozzle used in a steam cycle for equalizing thermodynamic conditions of two streams of steam having different pressures and temperatures is arranged in the direction of flow to have an inlet nozzle section I, Figs. 6 and 7, comprising separate inlet nozzles for the two streams in which the stream of lower pressure is caused to flow with super-critical velocity and the other stream to flow with substantially the same velocity, a pressure-equalizing section II in which the cross-section decreases in the direction of flow and the velocity of the streams remains unchanged, a convergent diffuser section III where the velocity of the combined stream is reduced to substantially the critical velocity while the pressure is increased, and a divergent diffuser section IV in which the velocity of the combined stream is still further decreased. The two inlet nozzles may be coaxially arranged one inside the other. In the inlet section I, the modification of the velocities of the streams is accompanied by a reduction of pressure, in the section II the velocity follows a sine function transversely of the axis and the pressure wave runs transversely of the axis, in the section III the reduction of velocity is accompanied by increase of pressure and in the section IV the further reduction of velocity is accompanied by a rise of pressure to that desired and equalization of temperature. If desired, nozzles of this kind may be arranged in series or parallel. Fig. 9 shows the equalizing nozzle AD incorporated in an installation comprising a turbine T with medium and low pressure stages Tm, Tn. Regenerative preheating is effected by passing some of the steam extracted from the turbine T to a further turbine Tv, the operating steam for which is branched from the feed to the nozzle AD after residual super-heat has been given up during its passage through heat-exchangers U and Vw 2  and evaporator Vd. This feed to the nozzle AD, which is at pressure P 2 ; joins the second stream which enters the nozzle at pressure p 1  after vaporization in the evaporator Vd of the condensate from turbine T v , through the pre-heaters Vw 1  and Vw 2 , and superheating in the superheater U and in the fluegas super-heater U 1 . The combined stream leaves the nozzle AD at the desired pressure and is further superheated by a fluegas superheater U 2  before passing to the turbine T. Part or whole of the condensate may be vaporized in an evaporator K arranged upstream of the nozzle. A reheating arrangement may be used between the stages Tm, Tn. In an alternative arrangement, an existing installation with a condensing extraction turbine can be enlarged by adding a high pressure backpressure turbine, the exhaust steam of which is partly supplied to the existing turbine and the other part is mixed in an equalizing nozzle with steam at higher pressure obtained by vaporizing the condensate of the existing turbine; the steam supplied by the nozzle is then supplied to the outlet of the added turbine.